/**
 * Marks the document as "JavaScript available".
 *
 * Every hidden state in this template — the scroll reveals, the stacked flow
 * panels, the pinned step track — is written under `html.js` in the
 * stylesheet. If the scripts fail to load, that class is never added and the
 * page stays fully readable: nothing is invisible, the flow panels sit one
 * after another, and the step track is an ordinary swipeable carousel.
 *
 * This file is loaded synchronously in <head>, before the first paint, which
 * is what prevents a flash of visible-then-hidden content.
 */
document.documentElement.classList.add("js");
